Definition of "mayfly"

Adult mayflies have large compound eyes and most have two pairs of wings. […] Mayfly nymphs are distinguished by their three tails (two cerci and a terminal filament) and the set of gills on each side of their abdomen.

2002, John Gooderham, Edward Tsyrlin, The Waterbug Book, page 132

Mayflies are fragile, gossamer-winged insects that arise from bodies of water and often swarm in great numbers.

2005, Terry Hellekson, Fish Flies: The Encyclopedia of the Fly Tier's Art, page 213

Stoneflies have negligible consumptive (thin solid line) and behavioral effects (thin dashed line) on mayfly abundance. Consumption by trout decreases the abundance of mayflies (solid line), but trout suppress mayfly emigration (drift) and thereby increase their abundance (thick dashed line).

2010, Barbara L. Peckarsky, J. David Allan, Angus R. McIntosh, Brad W. Taylor, “Chapter 9: Understanding the Role of Predation in Open Systems”, in Ian Billick, Mary V. Price, editors, The Ecology of Place, page 195

Dipping a French fry in her tomato ketchup, she admits that her name recognition could be higher. But it did spike a year ago during the mayfly premiership of Liz Truss.

2023 October 7, Jim Pickard, “It's not government that creates jobs”, in FT Weekend, Life & Arts, page 3